**Core Concept**
Cryptococcus species, particularly Cryptococcus neoformans, is a type of encapsulated yeast that causes cryptococcosis, primarily affecting immunocompromised individuals. Confirmation of the species is crucial for diagnosis and treatment. The main methods for identifying Cryptococcus species include various laboratory tests.

**Why the Correct Answer is Right**
Confirmation of Cryptococcus species is typically done by several laboratory tests, including:
- India ink staining: This method uses a negative stain to visualize the polysaccharide capsule surrounding the yeast cells, which is a characteristic feature of Cryptococcus neoformans.
- Lactophenol cotton blue staining: This staining method helps in visualizing the capsule and the morphology of the yeast cells.
- Agar culture: Cryptococcus species can be grown on various agar media, such as Sabouraud agar or cornmeal agar.
- Molecular methods: PCR (polymerase chain reaction) and DNA sequencing can be used to identify the species and confirm the diagnosis.

**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect as it is not a commonly used method for confirming Cryptococcus species.
**Option B:** This option is incorrect as it is not a specific method for confirming Cryptococcus species, but rather a general term for laboratory tests.
**Option C:** This option is incorrect as it is a method used for identifying the morphology of the yeast cells, but it is not the most specific method for confirming Cryptococcus species.

**Clinical Pearl / High-Yield Fact**
Cryptococcal meningitis is a serious and potentially life-threatening condition that requires prompt diagnosis and treatment. India ink staining is a simple and rapid method for confirming the presence of Cryptococcus neoformans in cerebrospinal fluid (CSF) samples.

**Correct Answer: D.**